Power transmission system for vehicle and vehicle comprising the same

ABSTRACT

A power transmission system for a vehicle and a vehicle including the same are provided. The power transmission system includes an engine unit configured to generate power, a transmission unit adapted to selectively coupled with the engine unit, and configured to transmit the power generated by the engine unit, a first motor generator coupled with the transmission unit, an output unit configured to transmit the power output by the transmission unit to at least one of front and rear wheels of the vehicle, a power switching device adapted to enable or interrupt a power transmitting between the transmission unit and the output unit, and a second motor generator configured to drive the at least one of the front and rear wheels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefits of Chinese PatentApplication Serial Nos. 201420058190.8 and 201410044502.4, both filedwith the State Intellectual Property Office of P. R. China on Jan. 30,2014. The entire content of the above-reference applications isincorporated herein by reference.

FIELD

The present disclosure relates to the field of vehicles, and moreparticularly to a power transmission system for a vehicle, and a vehicleincluding the power transmission system.

BACKGROUND

To reduce energy consumption, the development and utilization ofenergy-efficient vehicles have become a trend. As an energy-efficientvehicle, a hybrid vehicle is driven by at least one of an internalcombustion engine and a motor and has various operation modes, andconsequently may operate with improved transmission efficiency and fueleconomic efficiency.

However, in the related art, the power transmission system in the hybridvehicle is generally complex in structure, bulky, low in transmissionefficiency, and complicated in control strategy. For example, aplurality of gear shift actuating elements needs to be controlledsimultaneously during the gear shifting or mode switching.

SUMMARY

Embodiments of the present disclosure seek to solve at least one of theproblems existing in the related art to at least some extent.

Embodiments of the present disclosure provide a power transmissionsystem for a vehicle. The power transmission system includes an engineunit configured to generate power, and a plurality of input shafts, eachhaving a driving gear, wherein the engine unit is configured toselectively engage with one of the input shafts to transmit power to theone of the input shafts. The power transmission system further includesan output shaft configured to transfer the power from the input shafts,one or more linked gears configured to rotate differentially relative tothe output shaft, the linked gears including a plurality of gear partsconfigured to mesh with the driving gears on the input shaftsrespectively, an output unit configured to transmit the power from theoutput shaft to wheels of the vehicle, a synchronizer disposed on theoutput shaft, and configured to be selectively engaged with the linkedgear so as to output the power via the output unit to drive the wheelsof the vehicle, and a first motor generator coupled with one of theinput shafts or the output shaft.

With the power transmission system for the vehicle according toembodiments of the present disclosure, the power output by at least oneof the engine unit and the first motor generator may be output to theoutput unit via the synchronizer. Therefore, the power transmissionsystem according to embodiments of the present disclosure is compact instructure and easy to control.

Embodiments of the present disclosure further provide a vehicle. Thevehicle includes the abovementioned power transmission system.

Additional aspects and advantages of embodiments of present disclosurewill be given in part in the following descriptions, become apparent inpart from the following descriptions, or be learned from the practice ofthe embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages of embodiments of the presentdisclosure will become apparent and more readily appreciated from thefollowing descriptions made with reference to the drawings, in which:

FIG. 1 is a schematic diagram of an exemplary power transmission systemaccording to an embodiment of the present disclosure;

FIG. 2 is a schematic view of an exemplary power transmission systemaccording to an embodiment of the present disclosure;

FIG. 3 is a schematic view of an exemplary power transmission systemaccording to another embodiment of the present disclosure;

FIG. 4 is a schematic view of an exemplary power transmission systemaccording to another embodiment of the present disclosure;

FIG. 5 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 6 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 7 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 8 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 9 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 10 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 11 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 12 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 13 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 14 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 15 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 16 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 17 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 18 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 19 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure;

FIG. 20 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure; and

FIG. 21 is a schematic view of an exemplary power transmission systemaccording to yet another embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will be made in detail to embodiments of the presentdisclosure. The embodiments described herein with reference to drawingsare explanatory, illustrative, and used to generally understand thepresent disclosure. The embodiments shall not be construed to limit thepresent disclosure. The same or similar elements and the elements havingsame or similar functions are denoted by like reference numeralsthroughout the descriptions.

In the specification, unless specified or limited otherwise, relativeterms such as “central”, “longitudinal”, “lateral”, “front”, “rear”,“right”, “left”, “inner”, “outer”, “lower”, “upper”, “horizontal”,“vertical”, “above”, “below”, “up”, “top”, “bottom” as well asderivative thereof (e.g., “horizontally”, “downwardly”, “upwardly”,etc.) should be construed to refer to the orientation as then describedor as shown in the drawings under discussion. These relative terms arefor convenience of description and do not require that the presentdisclosure be constructed or operated in a particular orientation.

In the description of the present disclosure, it should be understoodthat, unless specified or limited otherwise, the terms “mounted,”“connected,” and “coupled” and variations thereof are used broadly andencompass such as mechanical or electrical mountings, connections andcouplings, also can be inner mountings, connections and couplings of twocomponents, and further can be direct and indirect mountings,connections, and couplings, which can be understood by those skilled inthe art according to the detail embodiment of the present disclosure.

In addition, terms such as “first” and “second” are used herein forpurposes of description and are not intended to indicate or implyrelative importance or significance or to imply the number of indicatedtechnical features. Thus, the feature defined with “first” and “second”may comprise one or more of this feature. In the description of thepresent disclosure, “a plurality of” means two or more than two, unlessspecified otherwise.

A power transmission system 100 according to embodiments of the presentdisclosure will be described in detail below with reference to FIGS.1-21. The power transmission system 100 is applicable to a vehicle, suchas a hybrid vehicle with an engine unit 1 and a motor generator.

As shown in, for example, FIGS. 1-2 and 17-19, the power transmissionsystem 100 according to embodiments of the present disclosure mayinclude an engine unit 1, a transmission unit 2 a, a first motorgenerator 41, a second motor generator 42, an output unit 5 and a powerswitching device (e.g., a synchronizer 6 in FIG. 2, a clutch 9 in FIG.17, etc.).

The transmission unit 2 a is adapted to selectively couple with theengine unit 1. The engine unit 1 may selectively output power generatedby the engine unit 1 to the transmission unit 2 a via the clutch 9.Alternatively, the transmission unit 2 a may also output, for example, astarting torque from the first motor generator 41 to the engine unit 1,so as to start the engine unit 1. In the context of the presentdisclosure, the phase “the transmission unit 2 a is coupled with theengine unit 1” means that the power can be transferred between theengine unit 1 and the transmission unit 2 a directly or via othercomponents, so that the coupling between the transmission unit 2 a andthe engine unit 1 is also referred to as power coupling.

The engine unit 1 generates energy by mixing liquid or gaseous fuel andair and then combusting the mixed fuel and air therein, and the energyis converted into mechanical energy. The engine unit 1 of the vehiclemay adopt a four-stroke gasoline or diesel engine. The engine unit 1 maygenerally include a block, a crank-connecting rod mechanism, a valvemechanism, a supply system, an ignition system, a cooling system, alubrication system and the like.

The block of engine unit 1 can be an assembled body of individualmechanisms and systems of the engine unit 1. The crank-connecting rodmechanism may convert the linear reciprocating motion of a piston intothe rotary motion of a crankshaft, and output a drive force. The valvemechanism is configured to charge or discharge a gas at a predeterminedtime, so as to ensure the smooth performing of each cycle of the engineunit 1. The supply system may supply a mixture of oil and gas to acylinder for combustion. The cooling system is configured to cool theengine unit 1, so as to ensure that the operating temperature of theengine unit 1 is within a suitable temperature range. The lubricationsystem is configured to lubricate individual motion pairs in the engineunit 1, so as to reduce the wear and energy loss.

It would be appreciated that the engine unit 1 as well as structures andoperation principles of individual sub-systems and sub-mechanisms of theengine unit 1 are well known to those skilled in the art, so thedetailed description thereof will be omitted here for clarity purpose.

The first motor generator 41 is coupled with the transmission unit 2 a.In other words, the first motor generator 41 cooperates with thetransmission unit 2 a to transmit the power. The first motor generator41 may drive the transmission unit 2 a, while the transmission unit 2 amay drive the first motor generator 41.

For example, the engine unit 1 may output at least a part of the powergenerated thereby to the first motor generator 41 via the transmissionunit 2 a, and the first motor generator 41 may generate electricity andconvert mechanical energy into electric energy to be stored in an energystorage component such as a battery pack. As another example, the firstmotor generator 41 may convert electric energy from the battery packinto mechanical energy, and output the mechanical energy to the outputunit 5 via the transmission unit 2 a to drive the vehicle.

The first motor generator 41 is a motor having functions of both a motorand a generator. As used herein, the term “motor generator” refers to amotor having functions of both a motor and a generator, unless specifiedotherwise.

The output unit 5 is configured to transfer power transmitted by thetransmission unit 2 a to wheels 200 (e.g. one of front and rear wheels210 and 220) of the vehicle. In short, the output unit 5 is adapted tooutput the power from the transmission unit 2 a.

The power switching device such as the synchronizer 6 is adapted toenable or interrupt power transmitting between the output unit 5 and thetransmission unit 2 a. In other words, the power switching device mayoutput the power output from the transmission unit 2 a to at least oneof front and rear wheels 210, 220 via the output unit 5, or the powerswitching device may also disconnect the transmission unit 2 a from theoutput unit 5 and the transmission unit 2 a may not output the power tothe front and/or rear wheels 210, 220 via the output unit 5 directly.

As shown in FIGS. 1-13, the second motor generator 42 is configured todrive the front and/or rear wheels 210, 220.

Therefore, when the output unit 5 is configured to drive the frontwheels 210 and the second motor generator 42 is also configured to drivethe front wheels 210, the vehicle having the power transmission system100 may be operable as a two-wheel drive vehicle. When the output unit 5is configured to drive the front wheels 210 and the second motorgenerator 42 is configured to drive the rear wheels 220, the vehiclehaving the power transmission system 100 may be operable as a four-wheeldrive vehicle, and may switch between a two-wheel drive mode and afour-wheel drive mode. When the output unit 5 is configured to drive thefront wheels 210 and the rear wheels 220 and the second motor generator42 is configured to drive the front wheels 210 or the rear wheels 220,the vehicle having the power transmission system 100 may be operable asa four-wheel drive vehicle.

With the power transmission system 100 according to embodiments of thepresent disclosure, the power output by at least one of the engine unit1 and the first motor generator 41 may be output to the output unit 5via the power switching device, and then output by the output unit 5 tothe front and/or rear wheels 210 and 220 of the vehicle.

Meanwhile, the second motor generator 42 may compensate for the torqueof the front wheels 210 or the rear wheels 220, and may also cooperatewith the engine unit 1 and the first motor generator 41 to drive thevehicle, thus increasing the number of operation modes of the vehicle.Therefore, the vehicle may be adapted to different operating conditions,thus achieving better fuel economic efficiency while reducing theemission of harmful gases.

In some embodiments, as shown in FIGS. 1-16, the power switching deviceis configured as a synchronizer 6, and the synchronizer 6 is adapted toselectively synchronize the output unit 5 and with transmission unit 2a, so as to output the power via the output unit 5 to drive the wheels200 of the vehicle.

Here, the function of the synchronizer 6 may be to synchronize theoutput unit 5 with the transmission unit 2 a, i.e. under the action ofthe synchronizer 6, the output unit 5 and the transmission unit 2 a mayoperate synchronously, such that the power from the transmission unit 2a may be output with the output unit 5 as a power output terminal.However, when the transmission unit 2 a and the output unit 5 are notsynchronized by the synchronizer 6, the power from the transmission unit2 a may not be output to the wheels 200 via the output unit 5 directly.

In short, the synchronizer 6 functions to switch the power. When thesynchronizer 6 is in an engaged state, the power from the transmissionunit 2 a may be output via the output unit 5 to drive the wheels 200;and when the synchronizer 6 is in a disengaged state, the transmissionunit 2 a may not transmit the power to the wheels 200 via the outputunit 5. In this way, by controlling the synchronizer 6 to switch betweenthe engaged state and the disengaged state, the switching of the drivemode of the vehicle may be realized.

Compared to a clutch, the synchronizer 6 has the following advantages.

When the synchronizer 6 is in a disengaged state, the power transmittingbetween the engine unit 1, the transmission unit 2 a, the first motorgenerator 41 and the wheels 200 can be severed, such that operationssuch as electricity generation, driving, and power/torque transmissionmay not influence each other, which can be very important in reducingthe energy consumption of the vehicle. The synchronizer 6 may meet thisrequirement well. However, incomplete separation of friction platesusually occurs in the clutch, thus increasing the friction loss andenergy consumption.

When the synchronizer 6 is in an engaged state, the synthesized(coupled) driving force of the engine unit 1 and the first motorgenerator 41 can be transferred to the wheels 200 after the torquemultiplication of the transmission unit 2 a, or the driving force of thewheels 200 can be transferred to the first motor generator 41 togenerate electricity, which may require that the power coupling devicetransmit a large torque and have high stability. The synchronizer 6 maymeet this requirement well. However, if a clutch is used, an oversizeclutch which does not match with the entire system (including an engine,a transmission, a motor, etc.) needs to be designed, thus increasing thearrangement difficulty, the weight and the cost, and having the risk ofslipping under the action of an impact torque.

Moreover, the first motor generator 41 may adjust the speed of thetransmission unit 2 a, for example, the first motor generator 41 mayadjust the speed of the transmission unit 2 a with the rotating speed ofthe output unit 5 as a target value, so as to match the speed of thetransmission unit 2 a with the speed of the output unit 5 in a timeefficient manner, thus reducing the time required by the synchronizationof the synchronizer 6 and reducing the energy loss. Meanwhile, no torqueengagement of the synchronizer 6 may be achieved, thus greatly improvingthe transmission efficiency, synchronization controllability andreal-time synchronization of the vehicle. In addition, the life of thesynchronizer 6 may be further extended, thus reducing the maintenancecost of the vehicle. Furthermore, the power transmission system 100according to embodiments of the present disclosure is compact instructure and easy to control.

In some embodiments, as shown in FIGS. 2, 6-7, 14, 15, 17, and 18, thetransmission unit 2 a includes a transmission power input part 21 a anda transmission power output part 22 a. The transmission power input part21 a is selectively engaged with the engine unit 1, to transmit thepower generated by the engine unit 1. The transmission power output part22 a is configured to output the power from the transmission power inputpart 21 a to the output unit 5 via the synchronizer 6.

As shown in FIGS. 2, 6-7, 14, 15, 17, and 18, the transmission powerinput part 21 a includes an input shaft (e.g., a first input shaft 21, asecond input shaft 22) and a driving gear 25 mounted on the input shaft,the input shaft is selectively engaged with the engine unit 1, totransmit the power generated by the engine unit 1. In other words, whenthe engine unit 1 needs to output the power to the input shaft, theengine unit 1 may be engaged with the input shaft, such that the poweroutput by the engine unit 1 may be transferred to the input shaft. Theengagement between the engine unit 1 and the input shaft may be achievedby means of a clutch (e.g., a dual clutch 31), which will be describedin detail below.

As shown in FIGS. 2, 6-7, 14, 15, 17, and 18, the transmission poweroutput part 22 a includes an output shaft 24, and a driven gear 26mounted on the output shaft 24 and configured to mesh with the drivinggear 25 on the input shaft.

As shown in FIGS. 2-5, the output shaft 24 is configured to output atleast a part of the power transmitted by the input shaft. Specifically,the output shaft 24 and the input shaft cooperate with each other totransmit the power. For example, the power transmission between theoutput shaft 24 and the input shaft may be realized by means of thedriving gear 25 and the driven gear 26.

It would be appreciated that the power transmission between the outputshaft 24 and the input shaft is not limited to this embodiment. In someembodiments, the manner of power transmission between the output shaft24 and the input shaft may be selected according to practicalapplications. For example, the power transmitting between the outputshaft 24 and the input shaft may also be realized by means of a belttransmission mechanism, or a rack and pinion transmission mechanism.

In some embodiments, the output shaft 24 is configured to transmit atleast a part of the power on the input shaft. For example, when thepower transmission system 100 is in a certain transmission mode where,for example, the first motor generator 41 generates electricity, a partof the power on the input shaft may be used for the electricitygenerating of the first motor generator 41, and the other part of thepower on the input shaft may be used to drive the vehicle to run.Certainly, all power on the input shaft may be used for the electricitygeneration of the first motor generator 41.

In some embodiments, the power transmitting between the first motorgenerator 41 and one of the input shaft and the output shaft 24 may bedirect or indirect. As used herein, the term “direct power transmission”means that the first motor generator 41 is directly coupled with acorresponding one of the input shaft and the output shaft 24 for powertransmitting, without using any intermediate transmission componentssuch as a speed changing device, a clutch device, or a transmissiondevice. For example, an output terminal of the first motor generator 41is directly connected rigidly with one of the input shaft and the outputshaft 24. The direct power transmission has the advantages ofeliminating the intermediate transmission components and reducing theenergy loss during the power transmission.

As used herein, the term “indirect power transmission” refers to anyother power transmitting manners other than the direct powertransmission, for example, the power transmitting by means ofintermediate transmission components such as a speed changing device, aclutch device, or a transmission device. The indirect power transmissionhas the advantages of enabling convenient arrangement and achieving thedesired transmission ratio by providing a speed changing device and thelike.

The output unit 5 may be used as a power output terminal of the outputshaft 24 for outputting the power on the output shaft 24. The outputunit 5 and the output shaft 24 may rotate differentially (i.e., at adifferent speed) and not synchronously. In other words, there can be arotating speed difference between the output unit 5 and the output shaft24, and the output unit 5 and the output shaft 24 are not fixed witheach other.

The synchronizer 6 is disposed on the output shaft 24. Specifically, asshown in FIGS. 1-6, the synchronizer 6 may include a splined hub 61 anda synchronizing sleeve 62. The splined hub 61 may be fixed on the outputshaft 24, such that the splined hub 61 can rotate synchronously with theoutput shaft 24, while the synchronizing sleeve 62 may move in an axialdirection of the output shaft 24 relative to the splined hub 61 so as toselectively engage with the output unit 5, such that the output unit 5can rotate synchronously with the output shaft 24. In this way, thepower may be transferred from the output unit 5 to the front and/or rearwheels 210, 220, thus driving the wheels 200. However, it would beappreciated that the structure of the synchronizer 6 is not limited tothis embodiment.

With the power transmission system 100 according to embodiments of thepresent disclosure, the power output by at least one of the engine unit1 and the first motor generator 41 may be output from the output unit 5by the engagement of the synchronizer 6, such that the powertransmission system 100 is compact in structure and easy to control.Moreover, during the switching of the operating modes of the vehicle, itis possible for the synchronizer 6 to switch from a disengaged state toan engaged state, and the first motor generator 41 may adjust therotating speed of the output shaft 24 with the rotating speed of theoutput unit 5 as a target value, so as to match the rotating speed ofthe output shaft 24 with the rotating speed of the output unit 5 in ashort time, thus facilitating the engagement of the synchronizer 6,greatly improving the transmission efficiency and reducing the energyloss. Furthermore, the radial friction force is much smaller than theaverage value in the related art or even there is no radial frictionforce during the engagement of the synchronizer 6.

In some embodiments, the output unit 5 is configured to drive a firstpair of wheels, there is a pair of second motor generators 42 configuredto drive the first pair of wheels. Further, the power transmissionsystem 100 further includes at least one third motor generator 43configured to drive a second pair of wheels. The first pair of wheels isone pair of a pair of front wheels 210 and a pair of rear wheels 220,and the second pair of wheels is the other pair of the pair of frontwheels 210 and the pair of rear wheels 220. For example, as shown inFIGS. 2-8, the first pair of wheels refers to the front wheels 210 ofthe vehicle, and the second pair of wheels refers to the rear wheels 220of the vehicle. It is understood that in other embodiments, the firstpair of wheels can refer to the rear wheels 220 and the second pair ofwheels can refer to the front wheels 210.

Therefore, the power transmission system 100 according to embodiments ofthe present disclosure has four types of power output sources, i.e. theengine unit 1, the first motor generator 41, the second motor generator42 and the third motor generator 43, in which the engine unit 1, thefirst motor generator 41 and the second motor generator 42 may beconfigured to drive one pair of wheels of the vehicle, and the thirdmotor generator 43 may be configured to drive the other pair of wheelsof the vehicle. Therefore, the vehicle having the power transmissionsystem 100 is a four-wheel drive vehicle.

Moreover, during the switching of operating modes of the vehicle, it ispossible for the synchronizer 6 to switch from the disengaged state tothe engaged state, and the first motor generator 41 may adjust therotating speed of the output shaft 24 with the rotating speed of theoutput unit 5 as a target value, so as to match the rotating speed ofthe output shaft 24 with the rotating speed of the output unit 5 in ashort time, thus facilitating the engagement of the synchronizer 6,greatly improving the transmission efficiency and reducing the energyloss.

Meanwhile, by provision of the second motor generator 42 and the thirdmotor generator 43, the second motor generator 42 and the third motorgenerator 43 may compensate for the torque of the wheels 200, which isindirectly reflected in the output of output unit 5. The second motorgenerator 42 and the third motor generator 43 may indirectly adjust therotating speed of the output unit 5. For example, when the synchronizer6 switches from the disengaged state to the engaged state, the secondmotor generator 42 and the third motor generator 43 may indirectlyadjust the rotating speed of the output unit 5 according torequirements, so as to match the rotating speed of the output shaft 24with the rotating speed of the output unit 5 in a short time, thusfacilitating the engagement of the synchronizer 6.

Furthermore, the second motor generator 42 and the third motor generator43 may cooperate with the first motor generator 41 to adjust therotating speed of the output unit 5 simultaneously, so as to synchronizethe rotating speed of the output shaft 24 and the rotating speed of theoutput unit 5 in a shorter time, thus facilitating the engagement of thesynchronizer 6 and greatly improving the transmission efficiency.

In short, the first motor generator 41 may adjust the rotating speed ofthe output unit 5 separately. In some embodiments, at least one of thesecond motor generator 42 and the third motor generator 43 may adjustthe rotating speed of the output unit 5 separately. In some embodiments,the first motor generator 41, the second motor generator 42 and thethird motor generator 43 may adjust the rotating speed of the outputunit 5 simultaneously.

In this way, the output of the power from the transmission unit 2 a maybe controlled by the engagement/disengagement of the synchronizer 6, andwhen the synchronizer 6 switches from the disengaged state to theengaged state, at least one of the first motor generator 41, the secondmotor generator 42 and the third motor generator 43 may compensate forthe speeds of the output shaft 24 and the output unit 5, so as to matchthe rotating speed of the output shaft 24 with the rotating speed of theoutput unit 5 rapidly, thus realizing no torque engagement of thesynchronizer 6 rapidly.

In some embodiments, as shown in FIGS. 2-9, there is a plurality of theinput shafts, i.e. two or more input shafts. The input shafts arecoaxially nested sequentially. For example, if there are N input shafts,the Kth input shaft is fitted over the (K−1)th input shaft, where N≧K≧2,and central axes of the N input shafts coincide with each other.

In some embodiments, as shown in FIGS. 2-5 and 7-9, when there are twoinput shafts, e.g. the first input shaft 21 and the second input shaft22, the second input shaft 22 is fitted over the first input shaft 21and central axes of the two input shafts coincide with each other. Insome embodiments, as shown in FIG. 6, when there are three input shafts,i.e. the first input shaft 21, the second input shaft 22 and a third theinput shaft 23, the third input shaft 23 is fitted over the second inputshaft 22, the second input shaft 22 is fitted over the first input shaft21, and central axes of the three input shafts coincide with each other.

When the engine unit 1 transmits the power to the input shaft or iscoupled with the input shaft for power transmitting, the engine unit 1may be selectively engaged with one of the input shafts. In other words,when the power from the engine unit 1 needs to be output, the outputterminal of the engine unit 1 may be engaged with one of the inputshafts, so as to rotate synchronously with the one of the input shafts.When the engine unit 1 does not need to operate or the engine unit 1 isidle, the engine unit 1 may be disconnected from individual input shaftsrespectively, i.e. the engine unit 1 is not coupled with any inputshaft, so as to interrupt the power transmission between the engine unit1 and individual input shafts.

Further, as shown in FIGS. 2-6 and 9, one driving gear 25 is fixed oneach input shaft, and the driving gear 25 rotates synchronously with theinput shaft. The fixing between the driving gear 25 and thecorresponding input shaft is not limited here, for example, the drivinggear 25 and the corresponding input shaft may be fixed by, for example,key fit or hot pressing, or may be formed integrally, as long as thesynchronous rotation of the driving gear 25 and the corresponding inputshaft is ensured.

In some embodiments, a plurality of driven gears 26 are fixed on theoutput shaft 24, and the driven gears 26 rotate synchronously with theoutput shaft 24. By way of example and without limitation, the fixingbetween the driven gear 26 and the output shaft 24 may be realized bykey fit or hot pressing, or may be formed integrally.

However, the present disclosure is not limited to this embodiment. Forexample, the number of the driving gears 25 on each input shaft is notlimited to one, and accordingly a plurality of driven gears 26 are fixedon the output shaft 24 to form a plurality of gears.

As shown in FIGS. 2-6 and 9, the driven gears 26 are configured to meshwith the driving gears 25 on the input shafts respectively. In oneembodiment, the number of the driven gears 26 may be the same as that ofthe input shafts. For example, when there are two driven gears 26, thereare two input shafts, such that the two driven gears 26 may beconfigured to mesh with the driving gears 25 on the two input shafts totransmit the power, so as to make the two pairs of gears form two gearsfor power transmission.

In some embodiments, three or more input shafts may be providedaccording to the power transmitting requirements, and each input shaftmay be provided with one driving gear 25. Therefore, the larger thenumber of the input shafts, the larger the number of the gears is, andthe wider range of the transmission ratio of the power transmissionsystem 100 is, so as to adapt to the power transmitting requirements ofvarious vehicles.

In some embodiments, as shown in FIGS. 2-5, the input shafts include thefirst input shaft 21 and the second input shaft 22. The second inputshaft 22 is fitted over the first input shaft 21. The second input shaft22 is a hollow shaft, and the first input shaft 21 is preferably a solidshaft. Alternatively, the first input shaft 21 may also be a hollowshaft.

In some embodiments, the first input shaft 21 may be supported bybearings. For example, a plurality of bearings can be disposed in anaxial direction of the first input shaft 21 at a position notinfluencing the assembly of other components. Similarly, the secondinput shaft 22 may also be supported by bearings.

Further, in some embodiments, as shown in FIGS. 2-5, a dual clutch 31 isdisposed between the engine unit 1 and the first and second input shafts21, 22. The dual clutch 31 may be a dry dual clutch 31 or a wet dualclutch 31.

The dual clutch 31 has an input terminal 313, a first output terminal311 and a second output terminal 312. The engine unit 1 is coupled withthe input terminal 313 of the dual clutch 31. Specifically, the engineunit 1 may be coupled with the input terminal 313 of the dual clutch 31via for example, a flywheel, a damper, or a torsion plate.

The first output terminal 311 of the dual clutch 31 is coupled with androtates synchronously with first input shaft 21. The second outputterminal 312 of the dual clutch 31 is coupled with and rotatessynchronously with the second input shaft 22.

The input terminal 313 of the dual clutch 31 may be a shell of the dualclutch 31, and the first output terminal 311 and the second outputterminal 312 of the dual clutch 31 may be two driven discs. The shellmay be disconnected from the two driven discs, such that the inputterminal 313 is disconnected from the first output terminal 311 and thesecond output terminal 312. When one driven disc needs to be engaged,the shell can be controlled to engage with the corresponding driven discto rotate synchronously with the driven disc, e.g. the input terminal313 is engaged with one of the first output terminal 311 and the secondoutput terminal 312, such that the power transmitted from the inputterminal 313 may be output via one of the first output terminal 311 andthe second output terminal 312. Typically, the shell is engaged with onedriven disc at a time.

It would be appreciated that the engagement of the dual clutch 31 isinfluenced by a control strategy. The control strategy may be setaccording to the desired power transmission mode, e.g. switching betweena mode in which the input terminal 313 is disconnected from the firstoutput terminal 311 and the second output terminal 312 and a mode inwhich the input terminal 313 is engaged with one of the first outputterminal 311 and the second output terminal 312.

In some embodiments, as shown in FIGS. 2-5, since the input shaft has aconcentric biaxial structure and each input shaft is provided with adriving gear 25, the transmission unit 2 a has two different gears, andthe engine unit 1 may output the power to the output unit 5 via the twogears, while the synchronizer 6 can remain in the engaged state toengage the output shaft 24 with the output unit 5.

During the gear shift, the synchronizer 6 may not need to be firstdisengaged and then move axially to engage with other gears. Accordingto embodiments of the present disclosure, only theengagement/disengagement of the dual clutch 31 needs to be controlled,while the synchronizer 6 can remain in the engaged state. In this way,when the engine unit 1 outputs the power to the output unit 5, only onegear shift actuating element, e.g. the dual clutch 31, needs to becontrolled, thus simplifying the control strategy greatly, reducing thenumber of engagement/disengagement times of, for example, thesynchronizer 6, and extending its life.

In some embodiments, the first motor generator 41 is configured tocooperate with one of the driving gear 25 and the driven gear 26 forpower transmission. In other words, indirect power transmission betweenthe first motor generator 41 and one of the input shaft and the outputshaft 24 is performed.

Further, in some embodiments, an intermediate transmission mechanism maybe disposed between the first motor generator 41 and the correspondinggear, and by way of example and without limitation, the intermediatetransmission mechanism may be a worm and worm gear transmissionmechanism, a one-stage or multi-stage gear pair transmission mechanism,or a chain wheel transmission mechanism, or may be a combination of theabove transmission mechanisms in the case of no conflicting. In thisway, the first motor generator 41 may be provided in different locationsas needed, thus reducing the arrangement difficulty of the first motorgenerator 41.

In order to facilitate the spatial arrangement, in some embodiments, thefirst motor generator 41 may transmit the power via an intermediate gear411. In some embodiments, as shown in FIGS. 2-3, indirect powertransmission between the first motor generator 41 and the driving gear25 on the first input shaft 21 via the intermediate gear 411 can beperformed. In some embodiments, as shown in FIG. 2, indirect powertransmitting between the first motor generator 41 and the driving gear25 on the second input shaft 22 via the intermediate gear 411 isperformed.

However, the present disclosure is not limited to this embodiment. Insome embodiments, the first motor generator 41 is configured to connectwith one of the first input shaft 21 and the output shaft 24. In someembodiments, as shown in FIG. 4, the first motor generator 41 isdirectly connected with the first input shaft 21. As another example, inthe example shown in FIG. 5, the first motor generator 41 is directlyconnected with the output shaft 24. Direct connection between the firstmotor generator 41 and the corresponding shaft may make the structure ofthe power transmission system 100 more compact, and decrease thecircumferential dimension of the power transmission system 100, suchthat the power transmission system 100 may be easily disposed in acompartment of the vehicle.

In some embodiments, as shown in FIG. 4, the first motor generator 41 isarranged coaxially with the first input shaft 21, and the first motorgenerator 41 is arranged coaxially with the engine unit 1, which allowsa rotation axis of a rotor of the first motor generator 41 tosubstantially coincide with a rotation axis of a crankshaft of theengine unit 1. Therefore, the power transmission system 100 becomes morecompact in structure.

In some embodiments, as shown in FIGS. 2-6, the output unit 5 mayinclude an output gear 51 and an engagement gear ring 52. The outputgear 51 may rotate relative to the output shaft 24, i.e. rotatedifferentially relative to the output shaft 24, and the engagement gearring 52 is fixedly connected with the output gear 51, i.e. theengagement gear ring 52 rotates synchronously with the output gear 51.

Therefore, when the synchronizer 6 needs to engage the output unit 5with the output shaft 24, the synchronizing sleeve 62 of thesynchronizer 6 may axially move toward the engagement gear ring 52, andafter the rotating speed of the output unit 5 is synchronized with therotating speed of the output shaft 24, the synchronizing sleeve 62 maybe engaged with the engagement gear ring 52, to form a rigid connectionbetween the output shaft 24, the synchronizer 6 and the output unit 5,so as to rotate the output shaft 24, the synchronizer 6 and the outputunit 5 synchronously.

In order to reduce the number of intermediate transmission components,to reduce the energy loss, and to enhance the transmission efficiency ofthe power transmission system 100, in some embodiments, as shown inFIGS. 2-6, the output gear 51 may be a driving gear of a main reducerand is configured to directly mesh with a driven gear 53 of the mainreducer to output the power, so as to drive the wheels 200. However, thepresent disclosure is not limited to this, and other intermediatetransmission components may also be disposed between the output gear 51and the main reducer.

In some embodiments, as shown in FIGS. 2-13, a differential 54 isdisposed between the first pair of wheels such as the front wheels 210.The differential 54 cooperates with the output unit 5 for powertransmitting. In some embodiments, the differential 54 is provided withthe driven gear 53 thereon, and the output gear 51 becomes the drivinggear of the main reducer configured to mesh with the driven gear 53,such that the power may be transferred to the two front wheels 210 viathe driving gear of the main reducer, the driven gear 53 of the mainreducer and the differential 54 sequentially.

The function of the differential 54 is to distribute the power to thetwo front wheels 210. The differential 54 may be a gear differential, amandatory locking differential, or the Torsen differential, which may beselected according to different vehicles.

In some embodiments, as shown in FIGS. 5-7 and 10, a pair of secondmotor generators 42 is disposed on two sides of the differential 54 backto back. For example, a pair of second motor generators 42 is disposedon two sides of the differential 54 and integrally formed with thedifferential 54. For example, the left second motor generator 42 can bedisposed between a left half shaft and the differential 54, and theright second motor generator 42 can be disposed between a right halfshaft and the differential 54. The power transmission system 100 inFIGS. 5-7 is operable in a four-wheel drive mode, and the powertransmission system 100 in FIG. 10 is operable in a two-wheel drivemode. It should be noted that in the following, when referring to “motorgenerators are disposed on two sides of the differential 54 back toback,” it means that the motor generators are disposed on two sides ofthe differential 54 respectively and integrally formed with thedifferential 54.

In other embodiments, as shown in FIGS. 2-4 and 9, the second motorgenerator 42 is a wheel-side motor. One of the second motor generators42 is disposed at an inner side of the left front wheel and the other ofthe second motor generators 42 is disposed at an inner side of the rightfront wheel, and the second motor generator 42 may transfer the power toa hub of a corresponding wheel via a gear mechanism. The powertransmission system 100 in FIGS. 2-4 is operable in a four-wheel drivemode, and the power transmission system 100 in FIG. 9 is operable in atwo-wheel drive mode.

In some embodiments, two third motor generators 43 are provided, and thethird motor generators 43 are a wheel-side motor, as shown in FIGS. 2and 5. In other words, in the examples shown in FIGS. 2 and 5, one ofthe third motor generators 43 is disposed at an inner side of the leftrear wheel, and the other of the third motor generators 43 is disposedat an inner side of the right rear wheel, and the third motor generator43 may transfer the power to a corresponding rear wheel via a gearmechanism.

In some embodiments, one third motor generator 43 is provided, and thethird motor generator 43 drives the second pair of wheels via a firstspeed changing mechanism 71. As shown in FIG. 7, the first speedchanging mechanism 71 can be a reducing mechanism, and the reducingmechanism may be a one-stage or multi-stage reducing mechanism. Thereducing mechanism may include, but is not limited to, a gear reducingmechanism, or a worm and worm gear reducing mechanism.

In this embodiment, the second pair of wheels may be connected with eachother via an axle which may have an integral structure. The third motorgenerator 43 may directly drive the integral axle via the first speedchanging mechanism 71, to drive the two wheels to rotate synchronously.

In some embodiments, two third motor generators 43 are provided, andeach third motor generator 43 drives one of the second pair of wheelsvia a second speed changing mechanism 72. As shown in FIGS. 3 and 6, thesecond speed changing mechanism 72 is a reducing mechanism, and thereducing mechanism may be a one-stage or multi-stage reducing mechanism.The reducing mechanism may include, but is not limited to, a gearreducing mechanism, or a worm and worm gear reducing mechanism.

In this embodiment, the two wheels in the second pair may be connectedwith the corresponding third motor generators 43 and the correspondingsecond speed changing mechanisms 72 via two half axles respectively. Inother words, one of the third motor generators 43 may drive acorresponding half axle via one of the second speed changing mechanisms72, so as to drive the wheel at an outer side of the half axle torotate.

In some embodiments, as shown in FIGS. 9-13, the power transmissionsystem 100 is operable in a two-wheel drive mode. In an example shown inFIG. 9, the output unit 5 drives the front wheels 210 (not shown in thefigure), and the second motor generator 42 is a wheel-side motor and isconfigured to drive the front wheels 210. In an example shown in FIG.10, the output unit 5 drives the front wheels 210, and the second motorgenerators 42 are disposed at two sides of the differential 54 back toback, for example, the second motor generators 42 are disposed at twosides of the differential 54 respectively and integrally formed with thedifferential 54. In an example shown in FIG. 11, the output unit 5drives the front wheels 210 (not shown in the figure), two second motorgenerators 42 are provided, and each second motor generator 42 drivesone rear wheel 220 via one fourth speed changing mechanism 74. In anexample shown in FIG. 12, the output unit 5 drives the front wheels 210(not shown in the figure), one second motor generator 42 is provided,and the second motor generator 42 drives the rear wheels 220 via onethird speed changing mechanism 73. In an example shown in FIG. 13, theoutput unit 5 drives the front wheels 210 (not shown in the figure), twosecond motor generators 42 are provided and are a wheel-side motor,which are configured to drive the rear wheels 220.

The third speed changing mechanism 73 may be the same as the first speedchanging mechanism 71. Similarly, the fourth speed changing mechanism 74may be the same as the second speed changing mechanism 72. Therefore,the third speed changing mechanism 73 and the fourth speed changingmechanism 74 will not be described in detail here.

In some embodiments, the power transmission system 100 may also includea battery pack 300. The battery pack 300 is connected with the firstmotor generator 41, the second motor generator 42 and the third motorgenerator 43 respectively. Therefore, the first motor generator 41 isdriven by the engine unit 1 to generate electricity or electric energyrecovered by the first motor generator 41 during the braking may besupplied to and stored in the battery pack 300, and electric energyrecovered by the second motor generator 42 and the third motor generator43 during the braking may also be supplied to and stored in the batterypack 300. When the vehicle is operated in an EV mode, the battery pack300 may supply electric energy to at least one of the first motorgenerator 41, the second motor generator 42 and the third motorgenerator 43. It would be appreciated that the dotted lines shown inFIG. 8 indicates that the battery pack 300 is electrically connectedwith the first motor generator 41, the second motor generator 42 and thethird motor generator 43 respectively.

In some embodiments, as shown in FIG. 8, the power transmission system100 comprises input shafts which include three shafts, e.g. the firstinput shaft 21, the second input shaft 22 and the third input shaft 23,the second input shaft 22 is fitted over the first input shaft 21, andthe third input shaft 23 is fitted over the second input shaft 22.

In this embodiment, the power transmission system 100 further includes atriple clutch 32. The triple clutch 32 has an input terminal 324, afirst output terminal 321, a second output terminal 322 and a thirdoutput terminal 323. The engine unit 1 is coupled with the inputterminal 324 of the triple clutch 32, the first output terminal 321 ofthe triple clutch 32 is coupled with the first input shaft 21, thesecond output terminal 322 of the triple clutch 32 is coupled with thesecond input shaft 22, and the third output terminal 323 of the tripleclutch 32 is coupled with the third input shaft 23.

In some embodiments, the input terminal 324 of the triple clutch 32 maybe a shell thereof, and the first, second and third output terminals321, 322, and 323 of the triple clutch 32 may be three driven discs. Theinput terminal 324 may be engaged with one of the first, second andthird output terminals 321, 322, and 323, or may be disconnected withthe first, second and third output terminals 321, 322, 323. It would beappreciated that the operation principle of the triple clutch 32 issimilar to that of the dual clutch 31, so the detailed descriptionthereof will be omitted here.

Other parts such as the power transmitting manner between the firstmotor generator 41 and the first input shaft 21 or the output shaft 24as well as the position and drive mode of the second motor generator 42and the third motor generator 43, are similar to those described withrespect to the dual clutch 31, so the detailed description thereof willbe omitted here.

In some embodiments, as shown in FIGS. 14-16, the power transmissionsystem 100 comprises a driven gear 26 which is configured as a linkedgear, and the linked gear 26 is freely fitted over the output shaft 24and rotates differentially relative to the output shaft 24. Thesynchronizer 6 is disposed on the output shaft 24 and may be selectivelyengaged with the linked gear 26.

In these embodiments, as shown in FIGS. 14-16, the power transmissionsystem 100 may include an engine unit 1, a plurality of input shafts, anoutput shaft 24, an output unit 5 (e.g., the driving gear 51 of the mainreducer), a synchronizer 6 and a first motor generator 41.

The power transmission system 100 in these embodiments may include adriven gear 26 which is configured as a linked gear and can be freelyfitted over the output shaft 24. With the output unit 5 fixed on theoutput shaft 24, the synchronizer 6 can be configured to engage with thelinked gear. In these embodiments, the arrangement of the first motorgenerator 41 may slightly differ from that of the first motor generator41 in the power transmission system 100 shown in FIGS. 2-13.

In some embodiments, as shown in FIGS. 14-16, a plurality of inputshafts are provided, the input shafts are provided with the drivinggears 25 thereon. The linked gear 26 is freely fitted over the outputshaft 24. The linked gear 26 has a plurality of gear parts (for example,the first gear part 261, and the second gear part 262), and the gearparts are configured to mesh with the driving gears 25 on the inputshafts respectively.

As shown in FIGS. 14-16, the output unit 5 is configured to output thepower from the output shaft 24. For example, the output unit 5 is fixedon the output shaft 24. In some embodiments, by way of example andwithout limitation, the output unit 5 may include the driving gear 51 ofthe main reducer.

The synchronizer 6 is disposed on the output shaft 24. The synchronizer6 is configured to selectively engage with the linked gear 26, so as tooutput the power via the output unit 5 to drive the wheels of thevehicle. The power transmission between the first motor generator 41 andone of the input shaft and the output shaft 24 may be direct orindirect.

In these embodiments, the function of the synchronizer 6 issubstantially the same as that of the synchronizer 6 shown in FIGS.2-13. The synchronizer 6 in these embodiments is configured to engagethe linked gear 26 with the output shaft 24, while the synchronizer 6shown in FIGS. 2-13 is configured to engage the output unit 5 with theoutput shaft 24.

Specifically, in these embodiments, the function of the synchronizer 6is to synchronize the linked gear 26 with the output shaft 24, so thatthe linked gear 26 and the output shaft 24 can operate synchronously tooutput the power from at least one of the engine unit 1 and the firstmotor generator 41 with the output unit 5 as a power output terminal.When the linked gear 26 and the output shaft 24 are not synchronized bythe synchronizer 6, the power from at least one of the engine unit 1 andthe first motor generator 41 may not be directly output to the wheels200 via the output unit 5.

In these embodiments, the synchronizer 6 functions to switch the power.When the synchronizer 6 is in an engaged state, the power from at leastone of the engine unit 1 and the first motor generator 41 may be outputvia the output unit 5 to drive the wheels 200; and when the synchronizer6 is in a disengaged state, the power from at least one of the engineunit 1 and the first motor generator 41 may not be transmitted to thewheels 200 via the output unit 5. In this way, by controlling thesynchronizer 6 to switch between the engaged state and the disengagedstate, the switching of the drive mode of the vehicle may be realized.

Moreover, the first motor generator 41 may adjust the speed of thelinked gear 26 with the rotating speed of the output shaft 24 as atarget value, so as to match the speed of the linked gear 26 with thespeed of the output shaft 24 in a time efficient manner, thus reducingthe time required by the synchronization of the synchronizer 6 andreducing the energy loss. Meanwhile, no torque engagement of thesynchronizer 6 may be achieved, thus greatly improving the transmissionefficiency, synchronization controllability and real-timesynchronization of the vehicle. In addition, the life of thesynchronizer 6 may be further extended, thus reducing the maintenancecost of the vehicle.

In addition, by using the linked gear 26, the power transmission system100 is more compact in structure and easy to arrange, and the number ofthe driven gears may be decreased so as to reduce the axial dimension ofthe power transmission system 100, thus reducing the cost and thearrangement difficulty.

Furthermore, the synchronizer 6 may be controlled by one separate fork,such that the control steps are simple and the reliability is high.

In some embodiments, the input shafts are coaxially nested, and eachinput shaft is provided with one driving gear 25. In some embodiments,the input shafts include a first input shaft 21 and a second input shaft22, and each input shaft is provided with one driving gear 25. Thelinked gear 26 is a double-linked gear, the double-linked gear 26 has afirst gear part 261 and a second gear part 262, and the first gear part261 and the second gear part 262 are configured to mesh with two drivinggears 25 respectively.

In some embodiments, a dual clutch 31 may be disposed between the engineunit 1 and the first and second input shafts 21 and 22. In someembodiments, the dual clutch 31 in the power transmission system 100shown in FIGS. 2-13. Alternatively, the dual clutch 31 may be providedwith a damping structure thereon, for example, the damping structure maybe arranged between a first output terminal and an input terminal of thedual clutch 31, to adapt to start the vehicle at a low gear.

As shown in FIGS. 14-16, direct or indirect power transmitting betweenan output terminal of the first motor generator 41 and one driving gearcan be performed.

For example, the power transmission system 100 in these embodimentsfurther includes an intermediate shaft 45. A first intermediate shaftgear 451 and a second intermediate shaft gear 452 are fixed on theintermediate shaft 45. One of the first and second intermediate shaftgears 431 and 432 are configured to mesh with one driving gear 25. Forexample, as shown in FIGS. 14-15, the first intermediate shaft gear 451is configured to mesh with the driving gear 25 on the second input shaft22. The present disclosure is not limited to these examples.

In some embodiments, direct power transmission between the outputterminal of the first motor generator 41 and one of the first and secondintermediate shaft gears 431 and 432, or indirect power transmissionbetween the output terminal of the first motor generator 41 and one ofthe first and second intermediate shaft gears 431 and 432 via anintermediate idler 44 can be performed. For example, as shown in FIG.14, indirect power transmission between the output terminal of the firstmotor generator 41 and the second intermediate shaft gear 452 via anintermediate idler 44 is performed. As another example, as shown in FIG.15, the output terminal of the first motor generator 41 is configured todirectly mesh with the second intermediate shaft gear 452 for powertransmission.

As shown in FIG. 16, the output terminal of the first motor generator 41is configured to directly mesh with one gear part of the linked gear 26.For example, the output terminal of the first motor generator 41 can beconfigured to directly mesh with the first gear part 261 for powertransmission.

However, it would be appreciated that, the present disclosure is notlimited to this embodiment. The position of the first motor generator 41may be designed according to practical requirements. For example, theposition of the first motor generator 41 may be the same as thatdescribed above, or may be as shown in FIGS. 2-13, which will not bedescribed in detail here.

As shown in FIGS. 14-15, the first gear part 261 inputs a torque to theengine unit 1 separately, from the second gear part 262, which may inputa torque to at least one of the engine unit 1 and the first motorgenerator 41.

As shown in FIGS. 14-16, an engagement gear ring 52 is fixed on a sideof the linked gear 26 facing the synchronizer 6, and the synchronizer 6is adapted to engage with the engagement gear ring 52, such that thelinked gear 26 is fixed with the output shaft 24 so as to rotatesynchronously with the output shaft 24.

In some embodiments, the plurality of the input shafts includes 3 inputshafts, the triple clutch and three input shafts are described above andshown in FIG. 8, so the detailed description thereof will be omittedhere. In some embodiments, as shown in FIGS. 19-21, the linked gear 26is a triple-linked gear. The linked gear 26 has a first gear part 261, asecond gear part 262 and a third gear part 263, and the first gear part261, the second gear part 262 and the third gear part 263 are configuredto mesh with the three driving gears 25 respectively.

In some embodiments, as shown in FIG. 21, the plurality of the inputshafts includes a first input shaft 21, a second input shaft 22 fittedover the first input shaft 21, and a third input shaft 23 fitted overthe second input shaft 22; and a fourth input shaft 27 fitted over thethird input shaft 23. Two linked gears 26 are provided and each linkedgear 26 is a double-linked gear having a first gear part 261 and asecond gear part 262, and the first gear part 261 and the second gearpart 262 configured to mesh with the corresponding driving gears 25respectively. The synchronizer 6 is disposed between the two linkedgears 26. The synchronizer is configured to selectively engage with theone of the linked gears 26. It can be understand that, the synchronizermay disengage with the two linked gears 26.

In some embodiments, a quadruple clutch includes an input terminalcoupled with the engine unit 1, a first output terminal coupled with thefirst input shaft 21, a second output terminal coupled with the secondinput shaft 22, a third output terminal coupled with the third inputshaft 23, and a fourth output terminal coupled with the fourth inputshaft 27. However, it would be appreciated that the connection betweenthe engine unit 1 and the input shafts is not limited to this particularexample.

In some embodiments, the power transmission system 100 includes a drivengear 26, which is configured as a linked gear and can be freely fittedover the output shaft 24. In these embodiments, the output unit 5 isfixed on the output shaft 24, and the synchronizer 6 is configured toengage with the linked gear 26. In some embodiments, the powertransmission system 100 may include a second motor generator 42 and athird motor generator 43, the arrangement of the second motor generator42 and the third motor generator 43 is substantially the same as that ofthe power transmission system 100 shown in FIGS. 2-13 and therefore itsdescription is omitted here.

In some embodiments, as shown in FIGS. 17-19, the synchronizer 6 of thepower transmission system can be replaced with a clutch 9.

Specifically, in these embodiments, as shown in FIGS. 17-19, the powerswitching device is a clutch 9. The clutch 9 is adapted to enable orinterrupt power transmission between the transmission unit 2 a and theoutput unit 5. For example, by the engagement of the clutch 9, thetransmission unit 2 a and the output unit 5 may operate synchronously,and the output unit 5 may output the power from the transmission unit 2a to the wheels 200. When the clutch 9 is in a disengaged state, thepower output by the transmission unit 2 a may not be directly output viathe output unit 5.

In these embodiments, the double-linked gear 26 is freely fitted overthe output shaft 24, and the output unit 5 is fixed on the output shaft24. The clutch 9 has a driving part (Cdriving in FIG. 17) and a drivenpart (Cdriven in FIG. 17). One of the driving part and the driven partof the clutch 9 is disposed on a linked gear such as a double-linkedgear 26, and the other of the driving part and the driven part of theclutch 9 is disposed on the output shaft 24. The driving part and thedriven part of the clutch 9 may be disengaged from or engaged with eachother. For example, as shown in FIG. 17, the driving part may bedisposed on the output shaft 24, and the driven part may be disposed onthe linked gear 26, but the present disclosure is not limited to thisembodiment.

Therefore, after the driving part and the driven part of the clutch 9are engaged with each other, the output shaft 24 is engaged with thedouble-linked gear 26 freely fitted over the output shaft 24, so as tooutput the power via the output unit 5. After the driving part and thedriven part of the clutch 9 are disengaged from each other, the linkedgear 26 is freely fitted over the output shaft 24, and the output unit 5does not transfer the power from the transmission unit 2 a.

With the power transmission system 100 according to embodiments of thepresent disclosure, since the synchronizer 6 is used for power switchingand has advantages of small volume, simple structure, large torquetransmission and high transmission efficiency, the power transmissionsystem 100 according to embodiments of the present disclosure has areduced volume, a more compact structure and high transmissionefficiency, and may meet the large-torque transmission requirements.

Meanwhile, by the speed compensation of at least one of the first motorgenerator 41, the second motor generator 42 and the third motorgenerator 43, no torque engagement of the synchronizer 6 may berealized, the ride comfort is better, the engagement speed is higher,and the dynamic response is faster. Compared to a clutch transmission inthe related art, larger torque may be withstood without failure, thusgreatly improving the stability and reliability of the transmission.

In some embodiments, as shown in FIGS. 2-3 and 5-8, four motorgenerators are used, and each motor generator is configured to drive onewheel. In the related art, a mechanical four-wheel drive vehicle mayonly achieve the torque distribution of front and rear wheels, and afull-time four-wheel drive vehicle may only achieve small difference ininstantaneous torque of left and right wheels. However, in theseembodiments, since four motors are used for driving the vehicle, +100%to −100% torque difference adjustment of the left and right wheel motorsmay be realized, thus greatly enhancing the steering stability duringthe high-speed turning, and improving the understeer and oversteerperformance. Furthermore, the turning radius of the vehicle may begreatly reduced by the rotation of the left and right wheels in oppositedirections when the vehicle runs at a low speed, such that the vehicleis easy to operate.

The construction and operating conditions of the power transmissionsystem 100 in various examples will be described below with reference toFIGS. 2-19.

Example 1

As shown in FIG. 2, the engine unit 1 is coupled with the input terminal313 of the dual clutch 31, the first output terminal 311 of the dualclutch 31 is coupled with the first input shaft 21, the second outputterminal 312 of the dual clutch 31 is coupled with the second inputshaft 22, and the second input shaft 22 is coaxially fitted over thefirst input shaft 21.

Each of the first input shaft 21 and the second input shaft 22 isprovided with one driving gear 25, and indirect power transmittingbetween the first motor generator 41 and the driving gear 25 on thesecond input shaft 22 is performed via one intermediate gear 411. Theoutput shaft 24 is provided with two driven gears 26, and the two drivengears 26 are meshed with the driving gears 25 on the first input shaft21 and the second input shaft 22, so as to form two gears.

The synchronizer 6 is disposed on the output shaft 24, the driving gear(i.e. the output gear 51) of the main reducer may rotate differentiallyrelative to the output shaft 24, the engagement gear ring 52 adapted tothe synchronizer 6 is fixed at a left side of the driving gear of themain reducer. The driving gear of the main reducer is externally meshedwith the driven gear 53 of the main reducer, and the driven gear 53 ofthe main reducer may be fixed on the differential 54, so as to transferthe power to the differential 54. The differential 54 distributes thepower and adaptively transfers the distributed power to half axles attwo sides of the vehicle, so as to drive the wheels 200.

Two second motor generators 42 constitute wheel-side motors configuredto drive two front wheels 210 respectively, and two third motorgenerators 43 constitute wheel-side motors configured to drive two rearwheels 220 respectively. That is, each of the four wheels is providedwith one wheel-side motor.

With the power transmission system 100 in this example, by theengagement or disengagement of the dual clutch 31, the power from theengine unit 1 may be transferred to the output shaft 24 with twodifferent transmission ratios respectively. The first motor generator 41may transfer the power to the output shaft 24 with a constanttransmission ratio via a shift gear set. When the synchronizer 6 is inan engaged state, the power from the output shaft 24 may be transferredto the front wheels 210 via the main reducer and the differential 54.When the synchronizer 6 is in a disengaged state, the power from theoutput shaft 24 may not be transferred to the front wheels 210. The twosecond motor generators 42 are wheel-side motors, and may directly drivetwo front wheels 210 respectively. The two third motor generators 43 arewheel-side motors, and may directly drive two rear wheels 220respectively.

The power transmission system 100 in this example may have at least thefollowing operating conditions: a pure EV (electric vehicle) operatingcondition of the third motor generator 43, a pure EV four-wheel driveoperating condition, a parallel operating condition, a series operatingcondition, and a braking/decelerating feedback operating condition.

First Operating Condition

This operating condition is a pure EV operating condition of the thirdmotor generator 43. The dual clutch 31 is in a disengaged state, thesynchronizer 6 is in a disengaged state, the engine unit 1, the firstmotor generator 41 and the second motor generator 42 do not operate, andtwo third motor generators 43 drive two rear wheels 220 respectively.This operating condition is mainly applicable to a situation where aload is small and an electric quantity of a battery is large, forexample, during uniform motions or under urban operating conditions.

This operating condition has the advantages that since the third motorgenerators 43 directly drive the rear wheels 220, compared to afront-wheel drive vehicle, the vehicle in this example has betteracceleration performance, gradeability and steering capability.Moreover, since the third motor generators 43 independently drive theleft rear wheel and the right rear wheel respectively, an electronicdifferential function may be achieved, thus increasing the operatingstability and reducing the amount of tire wear. In a front-wheel drivepart, since the association between the output gear 51 and the frontwheels 210 is interrupted by the synchronizer 6, there is no mechanicalloss in the front-wheel drive part, thus reducing the energy consumptionof the vehicle.

Second Operating Condition

This operating condition is a pure EV four-wheel drive operatingcondition. The dual clutch 31 is in a disengaged state, the synchronizer6 is in a disengaged state, the first motor generator 41 does notoperate, two second motor generators 42 are configured to drive twofront wheels 210 respectively, and two third motor generators 43 areconfigured to drive two rear wheels 220 respectively. This operatingcondition is mainly applicable to a situation where a load is large andan electric quantity of a battery is large, for example, duringacceleration, climbing, overtaking, or high-speed running.

This operating condition has the advantages of having better dynamicperformance than a single-motor drive, and having better economicefficiency and lower noise than a hybrid drive. A typical applicationhighlighting the advantages of this operating condition is trafficcongestion at a steep slope (mountain road).

Moreover, compared to a front-wheel drive vehicle and a rear-wheel drivevehicle, a pure EV four-wheel drive vehicle has better accelerationperformance, gradeability, handling performance and off-road capability.Since two second motor generators 42 and two third motor generators 43drive four wheels independently, the wheels may obtain different torquesand rotating speeds, so as to achieve the individual control on the fourwheels, thus maximizing the dynamic performance, operating stability andoff-road performance. Furthermore, when torques in different directionsare applied to the left and right wheels by corresponding motorgenerators, the in-situ steering of the vehicle may be realized.

Third Operating Condition

This operating condition is a parallel operating condition. The dualclutch 31 is in an engaged state, the synchronizer 6 is in an engagedstate, and the engine unit 1 and the first motor generator 41 transferthe power to the driving gear 51 of the main reducer via the shift gearset and the synchronizer 6, and the driving gear 51 of the main reducertransfers the power to the front wheels 210 via the differential 54,while two second motor generators 42 transfer the power to thecorresponding front wheels 210 and two third motor generators 43transfer the power to the corresponding rear wheels 220. This operatingcondition is mainly applicable to a situation where a load is thelargest, for example, during quick acceleration, or climbing steepslopes.

This operating condition has the advantages that five motor generatorsand the engine unit 1 drive the vehicle simultaneously, thus maximizingthe dynamic performance. Compared to a front-wheel drive vehicle and arear-wheel drive vehicle, a HEV four-wheel drive vehicle has betteracceleration performance, gradeability, handling performance andoff-road capability. Moreover, since the third motor generators 43independently drive the left rear wheel and the right rear wheelrespectively, an electronic differential function may be achieved, and amechanical differential in the related art is avoided, thus reducingparts while increasing the handling stability and reducing the amount oftire wear.

Fourth Operating Condition

This operating condition is a series operating condition. The dualclutch 31 is in an engaged state, the synchronizer 6 is in a disengagedstate, the engine unit 1 drives the first motor generator 41 via thedual clutch 31 and the shift gear set to generate electricity, thesecond motor generators 42 are configured to drive the front wheels 210respectively, and the third motor generators 43 are configured to drivethe rear wheels 220 respectively. This operating condition is mainlyapplicable to a situation where a load is medium and an electricquantity of a battery is small.

This operating condition has the advantages that, compared to afront-wheel drive vehicle and a rear-wheel drive vehicle, the vehicleunder the series (i.e. four-wheel drive series) operating condition hasbetter acceleration performance, gradeability, handling performance andoff-road capability. Since two second motor generators 42 and two thirdmotor generators 43 drive four wheels independently, the wheels mayobtain different torques and rotating speeds, so as to achieve theindividual control on the four wheels, thus maximizing the dynamicperformance, handling stability and off-road performance. Furthermore,when torques in different directions are applied to the left and rightwheels by corresponding motor generators, the in-situ steering of thevehicle may be realized. Moreover, the first motor generator 41 may keepthe engine unit 1 running in an optimal economic region through thetorque and speed control, thus reducing fuel consumption during theelectricity generation.

Fifth Operating Condition

This operating condition is a braking/decelerating feedback operatingcondition. The dual clutch 31 is in an engaged state, the synchronizer 6is in a disengaged state, the engine unit 1 drives the first motorgenerator 41 to generate electricity, the second motor generators 42brake the front wheels 210 and generate electricity, and the third motorgenerators 43 brake the rear wheels 220 and generate electricity. Thisoperating condition is mainly used for braking or decelerating thevehicle.

This operating condition has the advantages that, since the second motorgenerator 42 and the third motor generator 43 brake four wheelsrespectively during the decelerating or braking, whether the vehicle isturning or moving straightly, the power of each wheel may be fullyabsorbed, in the premise of ensuring the braking force and stability ofthe vehicle, thus maximizing the energy feedback. Moreover, because ofthe disengagement of the synchronizer 6, while the four motor generatorsbrake the four wheels respectively, the engine unit 1 and the firstmotor generator 41 may continue generating electricity, so as to enablea stable electricity generation state, avoid frequent switching, andextend the life of components.

Sixth Operating Condition

This operating condition is a series-parallel operating condition. Thedual clutch 31 is in an engaged state, the synchronizer 6 is in anengaged state, a part of the power from the engine unit 1 drives thefirst motor generator 41 via the dual clutch 31 and the shift gear setto generate electricity, the other part of the power from the engineunit 1 is transferred to the driving gear 51 of the main reducer via theshift gear set and the synchronizer 6, the second motor generators 42drive the front wheels 210 directly via the driving gear 51 of the mainreducer, and the third motor generators 43 drive the rear wheels 220respectively. This operating condition is mainly applicable to asituation where a load is large and an electric quantity of a battery issmall, for example, during acceleration or climbing. This operatingcondition has the advantages of exploiting all the power from the engineunit 1, ensuring the dynamic property of the vehicle while generatingelectricity, and maintaining the electric quantity of the battery.

The above six operating conditions may be switched, and typicalswitching between operating conditions is switching from the fourthoperating condition to the third operating condition, or switching fromthe fourth operating condition to the fifth operating condition.

Specifically, the switching from the fourth operating condition to thethird operating condition will be described as follows. For example,when it is necessary to quickly accelerate for overtaking or avoidingobstacles, according to the throttle demand of a driver, the powertransmission system 100 may switch from the fourth operating conditionto the third operating condition. At this time, the first motorgenerator 41 may adjust the rotating speed of the output shaft 24 withthe rotating speed of the driving gear of the main reducer as a targetvalue through the rotating speed control, so as to match the rotatingspeed of the output shaft 24 with the rotating speed of the driving gearof the main reducer as far as possible, thus facilitating the engagementof the synchronizer 6.

During the matching, the second motor generators 42 and the third motorgenerators 43 may respond to the needs of the driver to increase thetorque, such that the vehicle is accelerated, unlike a vehicle in therelated art, the vehicle needs not to be accelerated only when thesynchronizer 6 is in an engaged state. The torque compensation inadvance may greatly shorten the torque response time and improve theinstantaneous acceleration performance of the vehicle.

As another example, the switching from the fourth operating condition tothe fifth operating condition will be described as follows. When thevehicle needs to be braked or decelerated, according to the throttledemand or the brake pedal operation of the driver, the powertransmission system 100 may switch from the fourth operating conditionto the fifth operating condition. The second motor generators 42 and thethird motor generators 43 may meet the braking feedback requirements,and the feedback of the first motor generator 41 is not needed. At thistime, the second motor generators 42 and the third motor generators 43may respond to the needs of the driver to brake the wheels and feed backthe electric quantity, which need not be like a vehicle in the relatedart which feeds back the electric quantity only when the synchronizer 6is in an engaged state.

Meanwhile, the engine unit 1 and the first motor generator 41 may bekept generating electricity, under the braking operating condition andthe series operating condition. The torque compensation in advance maygreatly shorten the motor braking response time and increase thefeedback electric quantity.

Specifically, under complex road conditions, for example, when thevehicle runs uphill, downhill, on a bumpy road, or under a low adhesioncondition, the engagement of the synchronizer 6 can be difficult due tothe changing speed of the vehicle. Even if the first motor generator 41may adjust the rotating speed of the output shaft 24 through therotating speed control, since the rotating speed of the driving gear ofthe main reducer along with the speed of the vehicle is notcontrollable, the speed adjusting accuracy and rate of the first motorgenerator 41 may be reduced. Under such road conditions, since thesecond motor generators 42 and the third motor generators 43 maycompensate for the torque of the vehicle, the speed of the vehicle maybe stabilized effectively, thus improving the driving experience of thevehicle and simplifying the engagement of the synchronizer 6.

Example 2

As shown in FIG. 3, the power transmission system 100 includes two thirdmotor generators, wherein each third motor generator 43 drives acorresponding rear wheel 220 via one second speed changing mechanism 72.Other parts in this example are substantially the same as those in thepower transmission system 100 shown in FIG. 2, so the detaileddescription thereof will be omitted here. The operating conditions ofthe power transmission system 100 in this example are substantially thesame as those of the power transmission system 100 shown in FIG. 2,except that the power transfer between the third motor generators 43 andthe corresponding rear wheels 220 is performed via the second speedchanging mechanism 72, which will not be detailed here.

Example 3

As shown in FIG. 4, the power transmission system 100 includes one thirdmotor generator 43 which drives the rear wheels 220 via one first speedchanging mechanism 71. Other parts in this example are substantially thesame as those in the power transmission system 100 shown in FIG. 2, sothe detailed description thereof will be omitted here. The operatingconditions of the power transmission system 100 in this example aresubstantially the same as those of the power transmission system 100shown in FIG. 2, except that since two rear wheels 220 are driven by onethird motor generator 43 and one first speed changing mechanism 71, inthe premise of no new components, the differential rotation of the rearwheels 220 may not be realized by means of only one motor and one speedchanging mechanism, however, it would be appreciated that a differentialintegrally formed with the first speed changing mechanism 71 may beadded to realize the differential rotation of the two rear wheels 220.

Example 4

As shown in FIG. 5, the power transmission system 100 includes secondmotor generators 42 disposed on two sides of the differential 54 back toback respectively. Other parts in this example are substantially thesame as those in the power transmission system 100 shown in FIG. 2, sothe detailed description thereof will be omitted here. The operatingconditions of the power transmission system 100 in this example aresubstantially the same as those of the power transmission system 100shown in FIG. 2, which will not be detailed here.

Example 5

As shown in FIG. 6, the power transmission system 100 includes two thirdmotor generators 43, wherein each third motor generator 43 drives acorresponding rear wheel 220 via one second speed changing mechanism 72.Other parts in this example are substantially the same as those in thepower transmission system 100 shown in FIG. 2, so the detaileddescription thereof will be omitted here. The operating conditions ofthe power transmission system 100 in this example are substantially thesame as those of the power transmission system 100 shown in FIG. 2,which will not be detailed here.

Example 6

As shown in FIG. 7, the power transmission system 100 includes one thirdmotor generator 43 which drives the rear wheels 220 via one first speedchanging mechanism 71. Other parts in this example are substantially thesame as those in the power transmission system 100 shown in FIG. 2, sothe detailed description thereof will be omitted here. The operatingconditions of the power transmission system 100 in this example aresubstantially the same as those of the power transmission system 100shown in FIG. 2, except that since two rear wheels 220 are driven by onethird motor generator 43 and one first speed changing mechanism 71, inthe premise of no new components, the differential rotation of the rearwheels 220 may not be realized by means of only one motor and one speedchanging mechanism, however, it would be appreciated that a differentialintegrally formed with the first speed changing mechanism 71 may beadded to realize the differential rotation of the two rear wheels 220.

Example 7

As shown in FIG. 8, the power transmission system 100 includes a tripleclutch 32, three input shafts, and correspondingly three pairs ofdriving gears 25 and driven gears 26. Other parts in this example aresubstantially the same as those in the power transmission system 100shown in FIG. 2, so the detailed description thereof will be omittedhere.

Example 8

As shown in FIG. 9, the power transmission system 100 in this examplediffers from the power transmission system 100 shown in FIG. 2 in thatthe third motor generators 43 in the example shown in FIG. 2 areeliminated, and the power transmission system 100 in this example is ina two-wheel drive mode.

The power transmission system 100 in this example may have at least thefollowing operating conditions.

First Operating Condition

This operating condition is a pure EV operating condition of the secondmotor generator 42. The dual clutch 31 is in a disengaged state, thesynchronizer 6 is in a disengaged state, the engine unit 1 and the firstmotor generator 41 do not operate, and the second motor generators 42drive the front wheels 210 directly. This operating condition is mainlyapplicable to a situation where a load is small and an electric quantityof a battery is large, for example, during uniform motions or underurban operating conditions.

This operating condition has the advantages that, since the second motorgenerators 42 directly drive the front wheels 210, the transmissionchain is the shortest, and operating components is the fewest, thusachieving maximum transmission efficiency and minimum noise. Moreover,since the second motor generators 42 independently drive the left frontwheel 210 and the right front wheel 210 respectively, an electronicdifferential function may be achieved, thus increasing the handlingstability and reducing the amount of tire wear.

Second Operating Condition

This operating condition is a pure EV operating condition of threemotors. The dual clutch 31 is in a disengaged state, the synchronizer 6is in an engaged state, the engine unit 1 does not operate, the firstmotor generator 41 transfers the power to the driving gear 51 of themain reducer via the shift gear set and the synchronizer 6, and thedriving gear 51 of the main reducer evenly distributes the power to theleft and right front wheels 210 via the differential 54, while thesecond motor generators 42 directly drive the left and right frontwheels 210.

This operating condition is mainly applicable to a situation where aload is large and an electric quantity of a battery is large, forexample, during acceleration, climbing, overtaking, or high-speedrunning. This operating condition has the advantages of having betterdynamic performance than a single-motor drive, and having bettereconomic efficiency and lower noise than a hybrid drive. A typicalapplication highlighting the advantages of this operating condition istraffic congestion at a steep slope (mountain road).

Third Operating Condition

This operating condition is a parallel operating condition. The dualclutch 31 is in a disengaged state, the synchronizer 6 is in an engagedstate, the engine unit 1 and the first motor generator 41 transfer thepower to the driving gear 51 of the main reducer via the shift gear setand the synchronizer 6, the driving gear 51 of the main reducer evenlydistributes the power to the left and right front wheels 210 via thedifferential 54, and the second motor generators 42 directly drive theleft and right front wheels 210. This operating condition is mainlyapplicable to a situation where a load is the largest, for example,during quick acceleration, or climbing steep slopes.

This operating condition has the advantages that three motors and theengine unit 1 drive the vehicle simultaneously, thus maximizing thedynamic performance.

Fourth Operating Condition

This operating condition is a series operating condition. The dualclutch 31 is in an engaged state, the synchronizer 6 is in a disengagedstate, the engine unit 1 drives the first motor generator 41 via thedual clutch 31 and the shift gear set to generate electricity, thesecond motor generators 42 directly drive the front wheels 210. Thisoperating condition is mainly applicable to a situation where a load ismedium and an electric quantity of a battery is small.

This operating condition has the advantages that, since the second motorgenerators 42 directly drive the front wheels 210, the transmissionchain is the shortest, and operating components is the fewest, thusachieving maximum transmission efficiency and minimum noise.

Meanwhile, the first motor generator 41 may keep the engine unit 1running in an optimal economic region through the torque and speedcontrol, thus reducing fuel consumption during the electricitygeneration. Moreover, since the second motor generators 42 independentlydrive the left front wheel 210 and the right front wheel 210respectively, an electronic differential function may be achieved, thusincreasing the handling stability and reducing the amount of tire wear.

Fifth Operating Condition

This operating condition is a braking/decelerating feedback operatingcondition. The dual clutch 31 is in an engaged state, the synchronizer 6is in a disengaged state, the engine unit 1 drives the first motorgenerator 41 to generate electricity, the second motor generator 42directly brake the front wheels 210 and generate electricity. Thisoperating condition is mainly used for braking or decelerating thevehicle. This operating condition has the advantages that, since thesecond motor generator 42 brake two wheels respectively during thedecelerating or braking of the vehicle, the braking energy may beabsorbed to the largest extent and converted into electric energy, andthe engine unit 1 and the first motor generator 41 may continuegenerating electricity, so as to enable a stable electricity generationstate and avoid frequent switching.

The above five operating conditions may be switched, and typicalswitching between operating conditions is switching from the fourthoperating condition to the third operating condition, or switching fromthe fourth operating condition to the fifth operating condition.

Specifically, the switching from the fourth operating condition to thethird operating condition will be described as follows. For example,when it is necessary to quickly accelerate for overtaking or avoidingobstacles, according to the throttle demand of a driver, the powertransmission system 100 may switch from the fourth operating conditionto the third operating condition. At this time, the first motorgenerator 41 may adjust the rotating speed of the output shaft 24 withthe rotating speed of the driving gear 51 of the main reducer as atarget value through the rotating speed control, so as to match therotating speed of the output shaft 24 with the rotating speed of thedriving gear 51 of the main reducer as far as possible, thusfacilitating the engagement of the synchronizer 6.

During the matching, the second motor generators 42 may respond to theneeds of the driver to increase the torque, such that the vehicle isaccelerated, unlike a vehicle in the related art, the vehicle does notrequire the synchronizer 6 to be in an engaged state in order to beaccelerated. The torque compensation in advance may greatly shorten thetorque response time and improve the instantaneous accelerationperformance of the vehicle.

As another example, the switching from the fourth operating condition tothe fifth operating condition will be described as follows. When thevehicle needs to be braked or decelerated, according to the throttledemand or the brake pedal operation of the driver, the powertransmission system 100 may switch from the fourth operating conditionto the fifth operating condition. The second motor generators 42 maymeet the braking feedback requirements, and the feedback of the firstmotor generator 41 is not needed. At this time, the second motorgenerators 42 may respond to the needs of the driver to brake the wheelsand feed back the electric quantity. The vehicle does not require thesynchronizer 6 to be in an engaged state to feed back the electricquantity.

Meanwhile, the engine unit 1 and the first motor generator 41 may bekept generating electricity, under the braking operating condition andthe series operating condition. The torque compensation in advance maygreatly shorten the motor braking response time and increase thefeedback electric quantity.

Specifically, under complex road conditions, for example, when thevehicle runs uphill, downhill, on a bumpy road, or under a low adhesioncondition, the engagement of the synchronizer 6 is difficult due to thechanging speed of the vehicle. Even if the first motor generator 41 mayadjust the rotating speed of the output shaft 24 through the rotatingspeed control, since the rotating speed of the driving gear of the mainreducer along with the speed of the vehicle is not controllable, thespeed adjusting accuracy and rate of the first motor generator 41 may bereduced. Under these road conditions, since the second motor generators42 may compensate for the torque of the vehicle, the speed of thevehicle may be stabilized effectively, thus improving the drivingexperience of the vehicle and simplifying the engagement of thesynchronizer 6.

Example 9

As shown in FIG. 10, the power transmission system includes second motorgenerators 42 disposed on two sides of the differential 54 back to backrespectively. Other parts in this example are substantially the same asthose in the power transmission system 100 shown in FIG. 9, so thedetailed description thereof will be omitted here.

Example 10

As shown in FIG. 11, the power transmission system 100 in this examplediffers from the power transmission system 100 shown in FIG. 9 in thearrangement of the second motor generators 42. In this example, twosecond motor generators 42 are provided, and each second motor generator42 drives a corresponding rear wheel 220 via one fourth speed changingmechanism 74. Other parts in this example are substantially the same asthose in the power transmission system 100 shown in FIG. 9, so thedetailed description thereof will be omitted here.

The power transmission system 100 in this example may have at least thefollowing operating conditions.

First Operating Condition

This operating condition is a pure EV operating condition of the secondmotor generator 42. The dual clutch 31 is in a disengaged state, thesynchronizer 6 is in a disengaged state, the engine unit 1 and the firstmotor generator 41 do not operate, and each second motor generator 42drives one rear wheel 220 via a corresponding fourth speed changingmechanism 74. This operating condition is mainly applicable to asituation where a load is small and an electric quantity of a battery islarge, for example, during uniform motions or under urban operatingconditions. This operating condition has the advantages that, since thesecond motor generators 42 drive the rear wheels 220, compared to afront-wheel drive vehicle, the vehicle in this example has betteracceleration performance, gradeability and steering capability.Moreover, since the second motor generators 42 independently drive theleft rear wheel and the right rear wheel respectively, an electronicdifferential function may be achieved, thus increasing the handlingstability and reducing the amount of tire wear. In a front-wheel drivepart, since the association between the output gear 51 and the frontwheels 210 is interrupted by the synchronizer 6, there is no mechanicalloss in the front-wheel drive part, thus reducing the energy consumptionof the vehicle.

Second Operating Condition

This operating condition is a pure EV four-wheel drive operatingcondition. The dual clutch 31 is in a disengaged state, the synchronizer6 is in an engaged state, the engine unit 1 does not operate, the firstmotor generator 41 drives the front wheels 210 respectively, and thesecond motor generators 42 drive the rear wheels 220 respectively. Thisoperating condition is mainly applicable to a situation where a load islarge and an electric quantity of a battery is large, for example,during acceleration, climbing, overtaking, or high-speed running. Thisoperating condition has the advantages of having better dynamicperformance than a single-motor drive, and having better economicefficiency and lower noise than a hybrid drive. A typical applicationhighlighting the advantages of this operating condition is trafficcongestion at a steep slope (mountain road). Moreover, compared to afront-wheel drive vehicle and a rear-wheel drive vehicle, a pure EVfour-wheel drive vehicle has better acceleration performance,gradeability, handling performance and off-road capability. Moreover,since the second motor generators 42 independently drive the left rearwheel and the right rear wheel respectively, an electronic differentialfunction may be achieved, thus increasing the handling stability andreducing the amount of tire wear.

Third Operating Condition

This operating condition is a parallel operating condition. The dualclutch 31 is in a disengaged state, the synchronizer 6 is in an engagedstate, the engine unit 1 and the first motor generator 41 drive thefront wheels 210 simultaneously, and the second motor generators 42drive the rear wheels 220 respectively. This operating condition ismainly applicable to a situation where a load is the largest, forexample, during quick acceleration, or climbing steep slopes. Thisoperating condition has the advantages that two motor generators and theengine unit 1 drive the vehicle simultaneously, thus maximizing thedynamic performance. Compared to a front-wheel drive vehicle and arear-wheel drive vehicle, a HEV four-wheel drive vehicle has betteracceleration performance, gradeability, handling performance andoff-road capability. Moreover, since the second motor generators 42independently drive the left rear wheel and the right rear wheelrespectively, an electronic differential function may be achieved, thusincreasing the handling stability and reducing the amount of tire wear.

Fourth Operating Condition

This operating condition is a series operating condition. The dualclutch 31 is in an engaged state, the synchronizer 6 is in a disengagedstate, the engine unit 1 drives the first motor generator 41 to generateelectricity, and the second motor generators 42 drive the rear wheels220 respectively. This operating condition is mainly applicable to asituation where a load is medium and an electric quantity of a batteryis small. This operating condition has the advantages that, since thetwo second motor generators 42 independently drive the left rear wheeland the right rear wheel respectively, an electronic differentialfunction may be achieved, thus increasing the handling stability andreducing the amount of tire wear. Compared to a front-wheel drivevehicle, the vehicle under the series operating condition has betteracceleration performance, gradeability, and steering capability.Moreover, the first motor generator 41 may keep the engine unit 1running in an optimal economic region through the torque and speedcontrol, thus reducing fuel consumption during the electricitygeneration.

Fifth Operating Condition

This operating condition is a braking/decelerating feedback operatingcondition. The dual clutch 31 is in a disengaged state, the synchronizer6 is in an engaged state, the engine unit 1 does not operate, and thefirst motor generator 41 and the second motor generators 42 brake thevehicle and generate electricity simultaneously. This operatingcondition has the advantages that, since three motors brake the vehiclesimultaneously during the decelerating or braking of the vehicle, thebraking energy may be absorbed to the largest extent and converted intoelectric energy. By the disengagement of the dual clutch, the braking ofthe vehicle by the friction torque of the engine unit may be eliminated,so that more power is left to be absorbed by the motor. Because of thebraking feedback of the front-wheel drive and the rear-wheel drive, thebraking force may be distributed to front and rear motors in the premiseof ensuring the braking force of the vehicle, and more electric energymay be fed back compared to a front-wheel drive vehicle or a rear-wheeldrive vehicle. Moreover, two second motor generators 42 may control thebraking force independently, thus improving the handling stability ofthe vehicle during braking when turning, and further increasing thefeedback energy.

Similarly, the operating conditions of the power transmission system 100in this example may be switched, and typical switching between operatingconditions is switching from the fourth operating condition to the thirdoperating condition, or switching from the fourth operating condition tothe fifth operating condition. The switching between the operatingconditions of the power transmission system 100 in this example issimilar to that in the above examples, so the detailed descriptionthereof will be omitted here.

Example 11

As shown in FIG. 12, the power transmission system 100 includes onesecond motor generators 42, and the second motor generator 42 drives therear wheels 220 via one third speed changing mechanism 73. Other partsin this example are substantially the same as those in the powertransmission system 100 shown in FIG. 9, so the detailed descriptionthereof will be omitted here.

In this example, the second motor generator 42 may be used to drive thevehicle separately. At this time, the dual clutch 31 and thesynchronizer 6 are in a disengaged state. This operating condition ismainly applicable to a situation where a load is small and an electricquantity of a battery is large, for example, during uniform motions orunder urban operating conditions. This operating condition has theadvantages that, since the second motor generators 42 directly drive therear wheels 220 via the third speed changing mechanism 73, compared to afront-wheel drive vehicle, the vehicle in this example has betteracceleration performance, gradeability and steering capability. In afront-wheel drive part, since the association between the output gear 51and the front wheels 210 is interrupted by the synchronizer 6, there isno mechanical loss in the front-wheel drive part, thus reducing theenergy consumption of the vehicle. In a rear-wheel drive part, adifferential integrally formed with the third speed changing mechanism73 may also be provided.

In this example, the power transmission system 100 may also have a pureEV four-wheel drive operating condition. At this time, the dual clutch31 is in a disengaged state, the synchronizer 6 is in an engaged state,the engine unit 1 does not operate, the first motor generator 41 drivethe front wheels 210 respectively, and the second motor generator 42drives the rear wheels 220 respectively. This operating condition ismainly applicable to a situation where a load is large and an electricquantity of a battery is large, for example, during acceleration,climbing, overtaking, or high-speed running. This operating conditionhas the advantages of having better dynamic performance than asingle-motor drive, and having better economic efficiency and lowernoise than a hybrid drive. A typical application highlighting theadvantages of this operating condition is traffic congestion at a steepslope (mountain road). Moreover, compared to a front-wheel drive vehicleand a rear-wheel drive vehicle, a pure EV four-wheel drive vehicle hasbetter acceleration performance, gradeability, handling performance andoff-road capability.

In this example, the power transmission system 100 may also have aparallel operating condition. The dual clutch 31 is in an engaged state,the synchronizer 6 is in an engaged state, the engine unit 1 and thefirst motor generator 41 drive the front wheels 210 simultaneously, andthe second motor generator 42 drive the rear wheels 220. This operatingcondition is mainly applicable to a situation where a load is thelargest, for example, during quick acceleration, or climbing steepslopes. This operating condition has the advantages that two motorgenerators and the engine unit 1 drive the vehicle simultaneously, thusmaximizing the dynamic performance. Compared to a front-wheel drivevehicle and a rear-wheel drive vehicle, a HEV four-wheel drive vehiclehas better acceleration performance, gradeability, handling performanceand off-road capability.

In this example, the power transmission system 100 may also have aseries operating condition. The dual clutch 31 is in an engaged state,the synchronizer 6 is in a disengaged state, the engine unit 1 drivesthe first motor generator 41 to generate electricity, and the secondmotor generator 42 drive the rear wheels 220. This operating conditionis mainly applicable to a situation where a load is medium and anelectric quantity of a battery is small. This operating condition hasthe advantages that compared to a front-wheel drive vehicle, the vehicleunder the series operating condition has better accelerationperformance, gradeability, handling performance and steering capability.Moreover, the first motor generator 41 may keep the engine unit 1running in an optimal economic region through the torque and speedcontrol, thus reducing fuel consumption during the electricitygeneration.

In this example, the power transmission system 100 may also have abraking/decelerating feedback operating condition. The dual clutch 31 isin a disengaged state, the synchronizer 6 is in an engaged state, theengine unit 1 does not operate, and the first motor generator 41 and thesecond motor generator 42 brake the vehicle and generate electricitysimultaneously. This operating condition has the advantages that, sincetwo motors brake the vehicle simultaneously during the decelerating orbraking of the vehicle, the braking energy may be absorbed to thelargest extent and converted into electric energy. By the disengagementof the dual clutch, the braking of the vehicle by the friction torque ofthe engine unit may be eliminated, so that more power is left to beabsorbed by the motor. Because of the braking feedback of thefront-wheel drive and the rear-wheel drive, the braking force may bedistributed to front and rear motors in the premise of ensuring thebraking force of the vehicle, and more electric energy may be fed backcompared to a front-wheel drive vehicle or a rear-wheel drive vehicle.

Similarly, the operating conditions of the power transmission system 100in this example may be switched, and typical switching between operatingconditions is switching from the fourth operating condition to the thirdoperating condition, or switching from the fourth operating condition tothe fifth operating condition. The switching between the operatingconditions of the power transmission system 100 in this example issimilar to that in the above examples, so the detailed descriptionthereof will be omitted here.

Example 12

As shown in FIG. 13, the power transmission system 100 includes twosecond motor generators 42 which are wheel-side motors, and each secondmotor generator 42 drives a corresponding rear wheel 220. The powertransmitting manner in this example is similar to that shown in FIG. 11,and other parts in this example are substantially the same as those inthe power transmission system 100 shown in FIG. 9, so the detaileddescription thereof will be omitted here.

Example 13

As shown in FIG. 14, the engine unit 1 is coupled with the inputterminal 313 of the dual clutch 31, the first output terminal 311 of thedual clutch 31 is coupled with the first input shaft 21, the secondoutput terminal 312 of the dual clutch 31 is coupled with the secondinput shaft 22, and the second input shaft 22 is coaxially fitted overthe first input shaft 21.

Each of the first input shaft 21 and the second input shaft 22 isprovided with one driving gear 25 by fixing, the double-linked gear 26(i.e. a driven gear) is freely fitted over the output shaft 24, thefirst gear part 261 of the double-linked gear 26 is configured to meshwith the driving gear 25 on the first input shaft 21, and the secondgear part 262 of the double-linked gear 26 is configured to mesh withthe driving gear 25 on the second input shaft 22.

A first intermediate shaft gear 451 and a second intermediate shaft gear452 are fixed on the intermediate shaft 45. The first intermediate shaftgear 451 is configured to mesh with the driving gear 25 on the secondinput shaft 22. Indirect power transmitting between the output terminalof the first motor generator 41 and the second intermediate shaft gear452 via an intermediate idler 44 is performed.

The synchronizer 6 is disposed on the output shaft 24 and configured toengage with the double-linked gear 26. The driving gear 51 of the mainreducer is fixed on the output shaft 24. The driving gear 51 of the mainreducer is configured to externally mesh with the driven gear 53 of themain reducer, and the driven gear 53 of the main reducer may be fixed ona housing of the differential 54, so as to transfer the power to thedifferential 54. The differential 54 distributes the power andadaptively transfers the distributed power to half axles at two sides ofthe vehicle, so as to drive the wheels 200.

Example 14

As shown in FIG. 15, the engine unit 1 is coupled with the inputterminal 313 of the dual clutch 31, the first output terminal 311 of thedual clutch 31 is coupled with the first input shaft 21, the secondoutput terminal 312 of the dual clutch 31 is coupled with the secondinput shaft 22, and the second input shaft 22 is coaxially fitted overthe first input shaft 21.

Each of the first input shaft 21 and the second input shaft 22 isprovided with one driving gear 25, the double-linked gear 26 (i.e. adriven gear) is freely fitted over the output shaft 24, the first gearpart 261 of the double-linked gear 26 is configured to mesh with thedriving gear 25 on the first input shaft 21, and the second gear part262 of the double-linked gear 26 is configured to mesh with the drivinggear 25 on the second input shaft 22.

A first intermediate shaft gear 451 and a second intermediate shaft gear452 are fixed on the intermediate shaft 45. The first intermediate shaftgear 451 is configured to mesh with the driving gear 25 on the secondinput shaft 22. The output terminal of the first motor generator 41 isconfigured to directly mesh with the second intermediate shaft gear 452for power transmitting.

The synchronizer 6 is disposed on the output shaft 24 and configured toengage with the double-linked gear 26. The driving gear 51 of the mainreducer is fixed on the output shaft 24. The driving gear 51 of the mainreducer is configured to externally mesh with the driven gear 53 of themain reducer, and the driven gear 53 of the main reducer may be fixed ona housing of the differential 54, so as to transfer the power to thedifferential 54. The differential 54 distributes the power andadaptively transfers the distributed power to half axles at two sides ofthe vehicle, so as to drive the wheels 200.

Example 15

As shown in FIG. 16, the engine unit 1 is coupled with the inputterminal 313 of the dual clutch 31, the first output terminal 311 of thedual clutch 31 is coupled with the first input shaft 21, the secondoutput terminal 312 of the dual clutch 31 is coupled with the secondinput shaft 22, and the second input shaft 22 is coaxially fitted overthe first input shaft 21.

Each of the first input shaft 21 and the second input shaft 22 isprovided with one driving gear 25, the double-linked gear 26 (i.e. adriven gear) is freely fitted over the output shaft 24, the first gearpart 261 of the double-linked gear 26 is configured to mesh with thedriving gear 25 on the first input shaft 21, and the second gear part262 of the double-linked gear 26 is configured to mesh with the drivinggear 25 on the second input shaft 22. The output terminal of the firstmotor generator 41 is configured to directly mesh with the first gearpart 261 for power transmitting.

The synchronizer 6 is disposed on the output shaft 24 and configured toengage with the double-linked gear 26. The driving gear 51 of the mainreducer is fixed on the output shaft 24. The driving gear 51 of the mainreducer is configured to externally mesh with the driven gear 53 of themain reducer, and the driven gear 53 of the main reducer may be fixed ona housing of the differential 54, so as to transfer the power to thedifferential 54. The differential 54 distributes the power andadaptively transfers the distributed power to half axles at two sides ofthe vehicle, so as to drive the wheels 200.

Example 15

As shown in FIG. 17, the power transmission system 100 in this examplediffers from the power transmission system 100 shown in FIG. 14 in thatthe clutch 9 is provided instead of the synchronizer 6 of the powertransmission system 100 in FIG. 14, and the driving gear 51 of the mainreducer is fixed on the output shaft 24.

Example 17

As shown in FIG. 18, the power transmission system 100 in this examplediffers from the power transmission system 100 shown in FIG. 15 in thatthe clutch 9 is provided instead of the synchronizer 6 of the powertransmission system 100 in FIG. 15, and the driving gear 51 of the mainreducer is fixed on the output shaft 24.

Example 18

As shown in FIG. 19, the power transmission system 100 in this examplediffers from the power transmission system 100 shown in FIG. 16 in thatthe clutch 9 is provided instead of the synchronizer 6 of the powertransmission system 100 in FIG. 16, and the driving gear 51 of the mainreducer is fixed on the output shaft 24.

It should be noted that, as shown in FIGS. 14-19, in a variation of thelinked gear 26, the power transmission system 100 may further include atleast one of the second motor generator 42 and the third motor generator43 (not shown in FIGS. 14-19), and the arrangement of at least one ofthe second motor generator 42 and the third motor generator 43 may bethe same as that in FIGS. 2-13, for example, being in a wheel-side form,or being disposed at two sides of the differential back to back. Forexample, alternatively, the driving gear 51 of the main reducer of thepower transmission system 100 shown in FIGS. 14-19 may be configured todrive the front wheels 210, and the rear-wheel drive may be the same asthat shown in FIG. 12, i.e. the rear wheels 220 are driven by one secondmotor generator 42 and one reducing mechanism.

In some embodiments, the second motor generator 42 is configured todrive the front and/or rear wheels 210, 220.

In some embodiments, the second motor generator 42 is configured todrive the front wheels 210, and the third motor generator 43 isconfigured to drive the rear wheels 220.

Embodiments of the present disclosure further provide a vehicleincluding the abovementioned power transmission system 100. It would beappreciated that, other components (e.g., a driving system, a steeringsystem, and a braking system) of the vehicle according to embodiments ofthe present disclosure are well known to those skilled in the art, sothe detailed description thereof will be omitted here.

Reference throughout this specification to “an embodiment,” “someembodiments,” “one embodiment”, “another example,” “an example,” “aspecific example,” or “some examples,” means that a particular feature,structure, material, or characteristic described in connection with theembodiment or example is included in at least one embodiment or exampleof the present disclosure. Thus, the appearances of the phrases such as“in some embodiments,” “in one embodiment”, “in an embodiment”, “inanother example,” “in an example,” “in a specific example,” or “in someexamples,” in various places throughout this specification are notnecessarily referring to the same embodiment or example of the presentdisclosure. Furthermore, the particular features, structures, materials,or characteristics may be combined in any suitable manner in one or moreembodiments or examples.

Although explanatory embodiments have been shown and described, it wouldbe appreciated by those skilled in the art that the above embodimentscannot be construed to limit the present disclosure, and changes,alternatives, and modifications can be made in the embodiments withoutdeparting from spirit, principles and scope of the present disclosure.

What is claimed is:
 1. A power transmission system for a vehicle,comprising: an engine unit configured to generate power; a plurality ofinput shafts, each having a driving gear, wherein the engine unit isconfigured to selectively engage with one of the input shafts totransmit power to the one of the input shafts; an output shaftconfigured to transfer the power from the input shafts; one or morelinked gears configured to rotate differentially relative to the outputshaft, the linked gears including a plurality of gear parts configuredto mesh with the driving gears on the input shafts respectively; anoutput unit configured to transmit the power from the output shaft towheels of the vehicle; a synchronizer disposed on the output shaft, andconfigured to be selectively engaged with the linked gear so as tooutput the power via the output unit to drive the wheels of the vehicle;and a first motor generator coupled with one of the input shafts or theoutput shaft.
 2. The power transmission system according to claim 1,wherein the output unit is fixed on the output shaft.
 3. The powertransmission system according to claim 1, wherein the input shafts arecoaxially nested sequentially, and the driving gears are fixed on theinput shafts.
 4. The power transmission system according to claim 3,wherein the input shafts comprise: a first input shaft; a second inputshaft fitted over the first input shaft; and two driving gears fixed onthe first input shaft and the second input shaft respectively; whereinthe one or more linked gears comprise a double-linked gear, thedouble-linked gear comprising a first gear part and a second gear part,wherein the first gear part and the second gear part are configured tomesh with the two driving gears respectively.
 5. The power transmissionsystem according to claim 4, further comprising: a dual clutch, the dualclutch including: an input terminal coupled with the engine unit; afirst output terminal coupled with the first input shaft; and a secondoutput terminal coupled with the second input shaft.
 6. The powertransmission system according to claim 1, further comprising anengagement gear ring, the engagement gear ring being fixed on a side ofthe linked gear facing the synchronizer, and wherein the synchronizer isadapted to engage with the engagement gear ring.
 7. The powertransmission system according to claim 6, further comprising anintermediate shaft, the intermediate shaft comprising: a firstintermediate shaft gear configured to mesh with the driving gear on thesecond input shaft, and a second intermediate shaft gear; wherein one ofthe first and second intermediate shaft gears is configured to meshedwith one driving gear; wherein the first motor generator includes anoutput terminal configurable to couple with one of the first and secondintermediate shaft gears for direct power transmission, or to couplewith one of the first and second intermediate shaft gears via anintermediate idler for indirect power transmission.
 8. The powertransmission system according to claim 1, wherein the output unitcomprises a driving gear of a main reducer.
 9. The power transmissionsystem according to claim 1, wherein the input shafts comprise: a firstinput shaft; a second input shaft fitted over the first input shaft; athird input shaft fitted over the second input shaft; and three drivinggears fixed on the first, second and third input shafts respectively;wherein the one or more linked gears comprise a triple-linked gear, thetriple-linked gear comprising a first gear part, a second gear part anda third gear part, wherein the first gear part, the second gear part andthe third gear part are configured to mesh with the three driving gearsrespectively.
 10. The power transmission system according to claim 11,further comprising a triple clutch, the triple clutch including: aninput terminal coupled with the engine unit; a first output terminalcoupled with the first input shaft; a second output terminal coupledwith the second input shaft; and a third output terminal coupled withthe third input shaft.
 11. The power transmission system according toclaim 1, wherein the input shafts comprise: a first input shaft; asecond input shaft fitted over the first input shaft; a third inputshaft fitted over the second input shaft; a fourth input shaft fittedover the third input shaft; and four driving gears fixed on the first,second, third and fourth input shafts respectively; wherein two linkedgears are provided and each linked gear is a double-linked gear having afirst gear part and a second gear part, and the first gear part and thesecond gear part being configured to mesh with the corresponding drivinggears respectively; and wherein the synchronizer is disposed between thetwo linked gears.
 12. The power transmission system according to claim11, further comprising a quadruple clutch, the quadruple clutchcomprising: an input terminal coupled with the engine unit; a firstoutput terminal coupled with the first input shaft; a second outputterminal coupled with the second input shaft; a third output terminalcoupled with the third input shaft; and a fourth output terminal coupledwith the fourth input shaft.
 13. The power transmission system accordingto claim 1, further comprising a second motor generator configured todrive the front wheels or rear wheels of the vehicle.
 14. The powertransmission system according to claim 13, wherein the second motorgenerator is configured to drive the front wheels, and the powertransmission system further comprises a third motor generator configuredto drive the rear wheels of the vehicle.
 15. A vehicle comprising apower transmission system, the power transmission system comprising: anengine unit configured to generate power; a plurality of input shafts,each having a driving gear, wherein the engine unit is configured toselectively engage with one of the input shafts to transmit power to theone of the input shafts; an output shaft configured to transfer thepower from the input shafts; one or more linked gears configured torotate differentially relative to the output shaft, the linked gearsincluding a plurality of gear parts configured to mesh with the drivinggears on the input shafts respectively; an output unit configured totransmit the power from the output shaft to wheels of the vehicle; asynchronizer disposed on the output shaft, and configured to beselectively engaged with the linked gear so as to output the power viathe output unit to drive the wheels of the vehicle; and a first motorgenerator coupled with one of the input shafts or the output shaft.